Low temperature colouring method

ABSTRACT

The present invention relates to a method of colouring polymer substrates at low temperatures. The method comprises subjecting the polymer substrate that is to be coloured to a colouring liquor comprising a solvent in which the colourant has a high solubility and then adding a solvent in which the colourant has a low solubility, typically water.

The present invention relates to a method of colouring polymersubstrates at low temperatures. The method comprises subjecting thepolymer substrate that is to be coloured to a colouring liquorcomprising a solvent in which the colourant has a high solubility andthen adding a solvent in which the colourant has a low solubility,typically water. The method is particularly useful for dyeing polyesterfibres and polyester fibre blends with disperse dyes.

BACKGROUND

A large proportion of the textile products produced in the world todaycomprise polyesters. In particular poly(ethylene terephthalate) (PES)accounted for ˜58.5% (53.1×10⁶ T) of the 90.6×10⁶ T world textile fibredemand in 2015. The outstanding success and enduring popularity of PESfibres can be attributed to their generally excellent textilecharacteristics and high chemical resistance, coupled with the abilityof polyester fibre to be manufactured in virtually any physical form asrequired for different applications, which include blending with othertypes of fibre. In the latter context, a chief use of polyester fibresis in combination with cotton fibres. In such polycotton blendmaterials, the cotton component provides comfort, absorbency, etc.whilst the polyester constituent imparts strength and resilience as wellas stain-resistance.

Polyester fibres are dyed exclusively using disperse dyes, which furnisha wide shade gamut and display generally very good fastness propertieson polyester. Disperse dyes belong to several chemical classes,predominantly anthraquininoid, (AQ), and azo, as exemplified by C.I.Disperse Red 60 and C.I. Disperse Blue 165.

Disperse dyes typically have low aqueous solubility. Solubilityincreases, however, markedly with increasing temperature, as exemplifiedby C.I. Disperse Red 121: 3.3 0.00033 gL⁻¹ at 25° C.; 0.0088 gL⁻¹ at130° C. This is of significance for their application to polyester fibreunder High Temperature (HT) dyeing conditions.

The solubility of disperse dyes is greatly increased in the presence ofcommercial dispersing agents, a feature that forms the basis of both thefinishing process that is used to prepare commercial forms of the dyeand the application method that is employed in their application topolyester fibres under aqueous immersion processes. Commercial dispersedyes typically comprise up to 60% by mass dispersing agent, addingconsiderably to the cost of the dyes. Dispersing agents (examplesinclude lignin sulfonates or formaldehyde polycondensates orarylsulfonic acids) are not particularly environmentally friendly. Theremoval and disposal of such materials from the dyed textile fibre atthe end of dyeing adds considerably to the cost, energy efficiency andenvironmental risk of commercial dyeing.

Owing to the very low rate of diffusion of the dyes within PES fibres attemperatures up to the commercial boil (i.e. 98° C.), commerciallyacceptable rates of dyeing with disperse dyes are most commonly achievedby the use of elevated temperatures in the region of 130-140° C. in aprocess commonly referred to as High Temperature (HT) dyeing. Currently,the vast majority of polyester fibre is dyed using such immersionprocesses at 130-140° C. Because such high temperatures are required fordyeing, the dyeing process is energy-intensive and the machines that areutilised for dyeing must be able to operate at pressures >1 atmosphere;consequently, the machines are typically very expensive.

PES fibres contain small amounts of oligomer, principally the cyclictrimer tris(ethylene terephthalate), as well as smaller amounts of otheroligomeric compounds. Such compounds migrate to the fibre surface duringHT dyeing and can deposit on the surfaces of both the fibre and machineduring cooling, which can reduce the visual depth of shade brilliance ofdyeings; the removal of the compounds from the dyeing machineconstitutes an additional problem in immersion dyeing. The removal ofthe oligomers, in addition to the excess dye and the dispersing agents,is routinely achieved using a reduction clearing process in which thedyed material is treated with Na₂S₂O₄ and a non-ionic surfactant,typically with heating. This process adds additional time to the processas well as additional materials and energy. It also generatesenvironmentally unacceptable efluents, including Na₂S₂O₄ and, in thecase of azo-disperse dyes, aromatic amines biproducts.

A further limitation of HT dyeing methods is that many fabrics, andparticularly natural fabrics (e.g. wool, silk) and more sensitivemanmade fabrics (e.g. polyurethanes, for example, Lycra®) are not stableunder the high temperature conditions. Where polyesters are combined(either woven together as a blend or joined together as parts of agarment) with these materials, other less effective dyeing methods mustbe used (which can lead to discernible differential colour strengths forthe individual fabrics in the blend) or pre-dyed fabric must be blended,which is a complex and costly process. This means that for blends orgarments that are formed of more than one different material, the fibreshave to be dyed separately before being woven together or joinedtogether.

When PES was first introduced in the 1950s, the preferred dyeing methodused was carrier dyeing, in which a carrier, typically a low molar mass,solid organic compound, such as o-phenyl phenol, is included in theaqueous dyeing liquor. This carrier facilitates the dyeing of the fabricand allows the use of lower temperatures than HT dyeing, typically 98°C. However, the carriers often have detectable smells, they often impairthe light fastness of the dyed material and they also pose environmentalconcerns and, as a result, HT dyeing processes predominate commerciallynowadays and the use of carrier dyeing has steadily declined.

Disperse dyes are much more soluble in organic solvents than they are inwater. However, organic solvents are ineffective for disperse dyeingbecause the dye has a greater affinity for the solvent than it does forthe fibres. Consequently, when disperse dyes are applied from organicsolvents low dye uptake onto the fibres is achieved so that the depth ofshade that can be accessed using high temperature aqueous dyeingtechniques cannot be replicated using organic solvent based dyeingliquors.

It is not just in the dyeing of polyesters where improvements in dyeingcan be made. Methodologies for dyeing wool, silk and polyamide fibresare often carried out at high temperatures and usually require specificvalues of pH for their successful application, leading to the use ofadditional chemicals to control the pH. The methods can also be timeconsuming. For example, dyeing with vat dyes is a complicated,time-consuming, multi-stage process that involves several pH changes andrequires the use of environmentally questionable strong reducing agents.

In addition, dyeing auxiliaries are commonly used to assist aqueousimmersion dyeing processes. The assistance provided by a given dyeingauxiliary will typically relate to a specific aspect of dyeing, such aswetting, dye levelling, fibre protection, etc. Thus, many differenttypes of dyeing auxiliary are commonly used in aqueous dye application,such as dispersants, sequestrants, lubricants, etc.). For example,dyeing processes for polyester fibres typically utilise dispersingagents and surfactants which are added to the dyebath to aid dyedispersion and levelling, as discussed above. Also, the pH at whichdyeing is performed is commonly adjusted so as to be within a definedrange, such as slightly acidic (pH˜4.5-6.0), although selected dispersedyes are suitable for application at high pH (˜pH 9.5). Because aqueousdyebaths routinely contain many auxiliaries often in large amounts, thewastewater generated during immersion dyeing is likely to contain a widevariety of auxiliary chemicals; indeed, many of the auxiliaries that areutilised in immersion dyeing (such as s dispersing agents that are usedin polyester dyeing) are intended to be removed from the dyed materialat the end of dyeing, meaning that such chemicals will be present in thewastewater that ensues from dyeing processes. Although many strategieshave been explored for treating dyeing effluent that contains residualdyeing auxiliaries, no single treatment method is effective for allauxiliaries or types of dye/fibre system. An additional advantage ofcertain embodiments of the current invention is that it is possible toreduce the number and amount of dyeing auxiliaries that are used indyeing processes, thus offering savings in chemical costs as well asenvironmental advantages.

Although, the methods of the invention were developed for the dyeing offibre substrates, the inventors have found that they can be applied moregenerally to other polymer substrates.

BRIEF SUMMARY OF THE DISCLOSURE

In a first aspect of the invention is provided a method of colouring apolymer substrate, the method comprising:

-   -   a) subjecting the polymer substrate to a colouring liquor at a        temperature T1, T1 being below 100° C., said colouring liquor        comprising at least one colourant dissolved in a first solvent        system to provide the polymer substrate wetted with the        colouring liquor;    -   b) adding a second solvent system to the polymer substrate        wetted with the colouring liquor, without raising the        temperature above a temperature T2, T2 being below 100° C., to        provide the dyed polymer substrate wetted with a mixture of the        first solvent system and the second solvent system; and    -   c) separating the dyed polymer substrate from the mixture of the        first and second solvent systems and any remaining colourant;        wherein the colourant or each colourant is more soluble in the        first solvent system than in the second solvent system.

The polymer substrate may be a fibre substrate. The colourant may be adye. The inventors have found that greater depth of colour can beachieved using the same quantity of colourant when using the abovemethod than can be achieved using HT disperse dyeing methods. Thisgreater depth of colour is achieved at a lower temperature than used inconventional HT methods and it is not necessary to use dispersingagents. Thus, the method of the first aspect is likely to be less energyintensive, less costly and pose lower risk to the environment than knownHT methods. Also being a low temperature process it can be performed onor in the presence of sensitive natural and man-made fibres. Withoutwishing to be bound by theory, it is believed that the addition of thesecond solvent system to the solution of the colourant in the firstsolvent system lowers the solubility of the colourant in the solvents.This in turn generates a molecular dispersion from which uptake of thecolourant into the fibre is possible and indeed that is more favouredthan with the dispersions formed in HT dyeing methods.

The inventors also have found that when applied to the acid dyeing ofcertain substrates, the methods of the invention provide effectivedyeing without the use of added dyeing auxiliaries, at lowertemperatures and more quickly than traditional methods.

The lower temperatures used allow for the simultaneous colouring of morethan one polymer type at a time. The methods apply not just to dispersedyes but also to other types of colourant, including acid dyes, directdyes, reactive dyes and vat dyes. The inventors have shown that it ispossible to dye more than one polymer (e.g. fabric) type at a time usingthe methods of the invention, with different colourant beingsimultaneously used to colour different polymers (e.g. fabrics).

In a second aspect of the invention is provided a polymer (e.g. fibre)substrate obtainable (e.g. obtained) according to the method of thefirst aspect.

The Method

It may be that the total amount of the second solvent system is added asa single portion to the polymer (e.g. fibre) substrate wetted with thecolouring liquor. It may be that it is added continuously over apredetermined period of time. It may be that it is added portionwise.Thus, it may be that the total amount of the second solvent system isadded in a predetermined number of equal sized portions, a predeterminedperiod of time apart. The inventors have found that the portionwiseaddition of the second solvent system provides the most effectivecolouring. Without wishing to be bound by theory, it is believed thatthe portionwise addition provides a more controlled formation of themolecular dispersion of the colourant (e.g. dye). In certainembodiments, the inventors have observed 100% uptake of the colourantinto the substrate, leaving no colourant left in the resultant mixtureof the first solvent system and the second solvent system.

The second solvent system is added to cause the colourant to precipitateout of the colouring liquor. Typically, where the polymer substrate is afibre substrate, this precipitation will occur within the fibresubstrate

The number of equal sized portions of the second solvent system may bein the range from 2 to 10, e.g. in the range from 3 to 6.

The dyed polymer (e.g. fibre) substrate wetted with a mixture of thefirst solvent system and the second solvent system may be held at atemperature T3, T3 being below 100° C., for a predetermined period oftime after the addition of the second solvent system

Typically, the coloured (e.g. dyed) polymer (e.g. fibre) substratewetted with a mixture of the first solvent system and the second solventsystem will be cooled or allowed to cool to a temperature T4 before thecoloured (e.g. dyed) polymer (e.g. fibre) substrate is separated fromthe mixture of the first and second solvent systems and any remainingdye.

It may be that the total colouring (e.g. dyeing) time is less than 3hours. It may be that the total colouring (e.g. dyeing) time is lessthan 90 minutes. It may be that the total colouring (e.g. dyeing) timeis less than 45 minutes. It may be that the total colouring (e.g.dyeing) time is greater than 20 minutes. The total colouring (e.g.dyeing) time is the period of time from the first addition of the secondsolvent system to the cooling of the dyed polymer (e.g. fibre) substratewetted with a mixture of the first solvent system and the second solventsystem.

It may be that the step of subjecting the polymer (e.g. fibre) substrateto a colouring liquor involves spraying the colouring liquor onto thesubstrate (e.g. fibre) substrate. It may be that the step of subjectingthe polymer (e.g. fibre) substrate to a colouring liquor involvesplacing the substrate into the colouring liquor.

It may be that the step of adding the second solvent system to thepolymer (e.g. fibre) substrate wetted with the colouring liquor involvesspraying the second solvent system onto the polymer (e.g. fibre)substrate wetted with the colouring liquor. It may be that the step ofadding the second solvent system to the polymer (e.g. fibre) substratewetted with the colouring liquor involves adding the second solventsystem into a colouring liquor in which the substrate is located.

The method may comprise the step of dissolving the colourant (e.g. dye)in the first solvent system to form the colouring liquor.

It may be that the colouring liquor does not comprise a dispersingagent. Typical dispersing agents include anionic, polyelectrolyte,compounds (and mixtures thereof), such as lignin sulfonates orformaldehyde polycondensates of arylsulfonic acids (e.g. disodiummethylenebisnaphthalene sulfonate, sodium oleyl-p-anisidinesulfonate).It may be that the dyeing liquor does not comprise a carrier. Typicalcarriers include, for example, o-dichlorobenzene,1,2,4-trichlorobenzene, dimethyl phthalate, diallyl phthalate, o-phenylphenol, p-phenyl phenol, diphenyl, 1-methylnaphthalene, ethylenecarbonate and propylene carbonate. Thus, the colouring liquor mayconsist essentially of the at least one colourant (e.g. a dye, forexample a disperse dye) dissolved in the first solvent system (e.g. apolar organic solvent). Thus, where the invention comprises the step ofdissolving the colourant (e.g. dye) in the first solvent system to formthe colouring liquor, the colourant (e.g. dye) that is dissolved may besubstantially pure (e.g. greater than 90% or greater than 95% pure). Theinventors have found that excellent colour strength can be obtainedusing the method of the invention in the absence of a dispersing agentor a carrier.

It may be that the second solvent system does not comprise a dispersingagent. It may be that the second solvent system does not comprise acarrier. Thus, the second solvent system may consist essentially of thesolvent or solvents that form the second solvent system.

Alternatively, the colouring liquor and/or the second solvent system maycomprise at least one additive selected from: a dispersing agent, acarrier, a stabiliser, a surfactant, an antioxidant, a pHmodifier/buffer, lubricant, softener, hydrotope, wetting agent andmigrating agent. The colouring liquor and/or the second solvent systemmay comprise at least one additive selected from: a stabiliser, asurfactant, an antioxidant, a pH modifier/buffer, lubricant, softener,hydrotope, wetting agent and migrating agent.

T1 and T2 may be the same. T1, T2 and T3 may be the same.

T1 may be greater than 70° C. T1 may be greater than 80° C. T1 may begreater than 90° C.

T2 may be greater than 70° C. T2 may be greater than 80° C. T2 may begreater than 90° C.

T3 may be greater than 70° C. T3 may be greater than 80° C. T3 may begreater than 90° C.

T4 may be less than 70° C. T4 may be less than 60° C.T1 may be in therange 25° C. to 70° C. T2 may be in the range 25° C. to 70° C. T2 may bein the range 25° C. to 70° C. Certain types of colourant, andparticularly dyes used to colour natural fibres, such as, wool, silk andcotton, can be used effectively at temperatures below 70° C. using themethods of the invention.

The method may be conducted at a pressure of about 1 atm. The method maybe conducted at a pressure in the range from 0.9 atm to 1.5 atm. Themethod may be conducted at an elevated pressure, e.g. a pressure greaterthan 1 atm and up to 5 atm.

It may be that the weight ratio of the polymer (e.g. fibre) substrate tothe first solvent system is in the range from 4:1 to 1:4. It may be thatthe weight ratio of the polymer (e.g. fibre) substrate to the firstsolvent system is in the range from 3:1 to 1:3. It may be that theweight ratio of the polymer (e.g. fibre) substrate to the first solventsystem is in the range from 2:1 to 1:2.5. It may be that the weightratio of the polymer (e.g. fibre) substrate to the first solvent systemis in the range from 1:1 to 1:2. It may be that the weight ratio of thepolymer (e.g. fibre) substrate to the first solvent system is in therange from 1:0.1 to 1:15.

It may be that the ratio of the polymer (e.g. fibre) substrate to thetotal amount of the second solvent system is in the range from 3:1 to1:15. It may be that the weight ratio of the polymer (e.g. fibre)substrate to the total amount of the second solvent system is in therange from 2:1 to 1:10. It may be that the weight ratio of the polymer(e.g. fibre) substrate to the total amount of the second solvent systemis in the range from 1:1 to 1:4.

It may be that the weight ratio of the polymer (e.g. fibre) substrate tothe total amount of the first and second solvent systems is in the rangefrom 1:1 to 1:20. It may be that the weight ratio of the polymer (e.g.fibre) substrate to the total amount of the first and second solventsystems is in the range from 1:1 to 1:10. It may be that the weightratio of the polymer (e.g. fibre) substrate to the total amount of thefirst and second solvent systems is in the range from 1:2 to 1:5.

It may be that the amount of colourant (e.g. dye) used is in the rangefrom 0.5 to 10% of the mass of the polymer substrate (e.g. 0.5 to 10% onmass fibre). It may be that the amount of colourant (e.g. dye) used isin the range from 1 to 5% of the mass of the polymer substrate (e.g. 1to 5% on mass fibre).

Typically, the total volume of the first solvent system to which thepolymer (e.g. fibre) substrate is subjected is less than the totalvolume of the second solvent system to which the polymer (e.g. fibre)substrate is subjected. The ratio of the total volume of the firstsolvent system to the total volume of the second solvent system may bein the range 1:2 to 1:20. The ratio of the total volume of the firstsolvent system to the total volume of the second solvent system may bein the range 1:3 to 1:15. The ratio of the total volume of the firstsolvent system to the total volume of the second solvent system may bein the range 30:70 to 10:90.

The colouring process may be followed by reduction clearing, rinsing andoptionally further treatments depending on the nature of the substrate(e.g. whether the substrate is a single or multicomponent blend offibres), and end-use requirement. Exemplary further treatments includesoftening, heat setting, etc.

The Solvent Systems

The methods of the invention involve the use of two solvent systems. Thecolourant (e.g. dye) is more soluble in the first solvent system than itis in the second solvent system.

The first solvent system should be capable of dissolving at least onecolourant.

The first solvent system may be supercritical CO₂. The first solventsystem may be a surfactant (e.g. a polyethoxylated fatty acid or andfatty acid ester or a mixture thereof) or a solution of a surfactant inwater.

Preferably, however, the first solvent system may comprise an organicsolvent or a mixture of two or more organic solvents. The first solventsystem may be an organic solvent or a mixture of two or more organicsolvents. The first solvent system may be an organic solvent. The firstsolvent system may comprise a mixture of two or more organic solvents.Where the first solvent system comprises an organic solvent or a mixtureof two or more organic solvents, the inventors have shown that thepresence of water is tolerated in the first solvent system but,typically, the first solvent system may comprise water but the waterwill typically represent less than 50% (e.g. less than 10%) by totalweight of the first solvent system. Thus, the first solvent system maycomprise less than 5% (e.g. less than 1%) water. The first solventsystem may comprise a mixture of water and an organic solvent.

The first solvent system may be an organic solvent having a molecularweight below 200 or a mixture of two or more organic solvents eachhaving a molecular weight below 200. The first solvent system may be anorganic solvent having a molecular weight below 175 or a mixture of twoor more organic solvents each having a molecular weight below 175. Thefirst solvent system may be an organic solvent having a molecular weightbelow 150 or a mixture of two or more organic solvents each having amolecular weight below 150. The first solvent system may be an organicsolvent having a molecular weight below 120 or a mixture of two or moreorganic solvents each having a molecular weight below 120. The firstsolvent system may be an organic solvent having a molecular weight below100 or a mixture of two or more organic solvents each having a molecularweight below 100. The first solvent system may be an organic solventhaving a molecular weight below 80 or a mixture of two or more organicsolvents each having a molecular weight below 80. The first solventsystem may be an organic solvent having a molecular weight above 80 or amixture of two or more organic solvents each having a molecular weightabove 80.

The first solvent may be an organic solvent that is a liquid at 25° C.and 1 atm or a mixture of two or more organic solvents each of which isa liquid at 25° C. and 1 atm. The first solvent may be an organicsolvent that is a liquid at 0° C. and 1 atm or a mixture of two or moreorganic solvents each of which is a liquid at 0° C. and 1 atm.

The first solvent system may be selected from: a non-polar organicsolvent (examples include pentane, hexane, benzene, toluene,dichloromethane, cyclohexane, heptane, CCl₄ etc), a polar aproticsolvent (e.g. acetone, methyl-t-butylketone, N-methylpyrollidinone,N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran,diethylether, ethylacetate, dimethylsulfoxide, diethylene glycol diethylether, ethylene glycol diacetate etc.) and a protic polar solvent (e.g.ethanol, methanol, propanol, isopropanol, ethylene glycol, glycerol,triethylene glycol monomethyl ether, dipropylene glycol methyl ether,1-methoxy-2-propanoletc) or a mixture thereof. The first solvent systemmay comprise a polar organic solvent or a mixture of two or more polarorganic solvents. The first solvent system may be a polar organicsolvent or a mixture of two or more polar organic solvents. The firstsolvent system may comprise a polar aprotic organic solvent or a mixtureof two or more polar aprotic organic solvents. The first solvent systemmay be an organic solvent comprising an ether group or a mixture of twoor more organic solvents comprising an ether group. The first solventsystem may be an organic solvent comprising both an ether group and ahydroxy group or a mixture of two or more organic solvents comprisingboth an ether group and a hydroxy group. The first solvent system may bea polar aprotic organic solvent or a mixture of two or more polaraprotic organic solvents. The first solvent system may comprise anorganic solvent that comprises carbon, hydrogen, oxygen, nitrogen andsulphur or a mixture of two or more organic solvents that comprisecarbon, hydrogen, oxygen, nitrogen and sulphur. The first solvent systemmay comprise an organic solvent that comprises carbon, hydrogen andoxygen or a mixture of two or more organic solvents that comprisecarbon, hydrogen and oxygen.

The first solvent system may comprise acetone. The first solvent systemmay be acetone. The first solvent system may be a mixture of acetone andone or more other polar organic solvent, e.g. a mixture of acetone andethanol.

The first solvent system may comprise DMSO. The first solvent system maybe DMSO. The first solvent system may be a mixture of DMSO and one ormore other polar organic solvent, e.g. a mixture of DMSO and ethanol ora mixture of DMSO and acetone.

The first solvent system may comprise glycerol. The first solvent systemmay be glycerol. The first solvent system may be a mixture of glyceroland one or more other polar organic solvent, e.g. a mixture of acetoneand glycerol.

The first solvent system may comprise a solvent selected from ethyleneglycol diacetate, triethylene glycol monomethyl ether, dipropyleneglycol methyl ether and 1-methoxy-2-propanol. The first solvent systemmay be a solvent selected from ethylene glycol diacetate, triethyleneglycol monomethyl ether, dipropylene glycol methyl ether and1-methoxy-2-propanol or a mixture thereof.

The first solvent system may comprise a solvent selected from glycerol,ethylene glycol diacetate, triethylene glycol monomethyl ether,dipropylene glycol methyl ether and 1-methoxy-2-propanol. The firstsolvent system may be a solvent selected from glycerol, ethylene glycoldiacetate, triethylene glycol monomethyl ether, dipropylene glycolmethyl ether and 1-methoxy-2-propanol or a mixture thereof.

The second solvent system should be one in which the colourant (e.g.dye) is poorly soluble. The second solvent system may be an organicsolvent in which the colourant (e.g. dye) is less soluble than thecolourant (e.g. dye) is in the first solvent system. Typically, thesecond solvent system comprises water. The second solvent system may bewater or an aqueous solution. The second solvent system may be a mixtureof water or an aqueous solution and an organic solvent. The secondsolvent system may be water. The second solvent may comprise a mixtureof two or more organic solvents.

Where the second solvent system is an aqueous solution it may be asolution of an electrolyte, an acid, a base or a buffer or a mixture ofan electrolyte with an acid, a base or a buffer.

Suitable electrolytes include NaCl, Na₂SO₄, ammonium sulfate and othersthat are commonly used in the application of dyes by dyeing.

Suitable bases include Na₂CO₃, NaHCO₃, K₂CO₃, KOH, NaOH and others thatare commonly used in the application of dyes by dyeing. Suitable acidsinclude acetic acid, formic acid, and others that are commonly used inthe application of dyes by dyeing.

Suitable buffers include those based upon citrate, phosphate, acetateand others that are commonly used in the application of dyes by dyeing.

Electrolytes are particularly useful when using a reactive dye, a vatdye or a direct dye.

Bases are particularly useful when using a reactive dye.

It may be that the first solvent system is miscible with the secondsolvent system. Thus, where the second solvent system is or compriseswater, the first solvent system may be water miscible.

Both the first and second solvent system are typically selected suchthat the polymer (e.g. fibre) substrate is not soluble in either thefirst or second solvent system.

Typically, the total volume of the first solvent system to which thepolymer (e.g. fibre) substrate is subject is less than the total volumeof the second solvent system to which the polymer (e.g. fibre) substrateis subjected. The ratio of the total volume of the first solvent systemto the total volume of the second solvent system may be in the range1:1.1 to 1:10. The ratio of the total volume of the first solvent systemto the total volume of the second solvent system may be in the range 1:2to 1:20. The ratio of the total volume of the first solvent system tothe total volume of the second solvent system may be in the range 1:3 to1:15. The ratio of the total volume of the first solvent system to thetotal volume of the second solvent system may be in the range 30:70 to10:90.

The Substrate

The polymer substrate may comprise natural, man-made and/or syntheticpolymers of organic or inorganic derivation, including, polypeptides,polysaccharides, hydrocarbons, elastomers, thermosets andthermoplastics, as exemplified by, but not limited to, polymers such ascollagen, keratin, cellulosics, alginates, polysulfide, polyamide,poly(lactic acid), polyvinyl chloride, polyacrylonitrile, polyethylene,polypropylene, polystyrene, polyurethane, aramid and polyimide.

The polymer substrate may take any solid physical form, includingpowder, pellet, sheet, film, fibre or any irregular shape. The polymersubstrate may be a moulded plastic shape, e.g. a car bumper or a pair ofspectacles. The polymer substrate may be a 3D printed object.

The polymer substrate may comprise more than one type of polymer. Thepolymer substrate may comprise two or more polymers present conjointlyin various mixtures formed by physical blending, mixing, dissolution,precipitation, the interconnection of moulded or 3D printed parts, etc.

The inventors have found that the methods of the invention can be usedto simultaneously colour different polymers with different types andclasses of colourant.

The polymer substrate may be a fibre substrate, e.g. a yarn, a fabric ora garment or part of a garment.

The fibre substrate may comprise synthetic fibres or natural fibres or amixture thereof. The fibre substrate may comprise fibres selected from:a polyester, a polyamide, a polyurethane, a polyalkylene, apolyacrylonitrile, wool, silk, natural or regenerated cellulose,cellulose ester, hair, polyvinyl chloride, carbon or a mixture thereof.

Exemplary polyesters include poly(ethylene terephthalate) (PES),poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate)(PTT). Exemplary polyurethanes include Lycra®. Exemplary polyamidesinclude nylon.

The fibre substrate may be or may comprise polyamide fibres, e.g. nylonfibres.

The fibre substrate may comprise polyester fibres or a mixture of apolyester with a fibre selected from cotton, wool, silk and polyurethane(e.g. Lycra®). The fibre substrate may comprise PES fibres or a mixtureof PES with a fibre selected from cotton, wool, silk and polyurethane(e.g. Lycra®). The fibre substrate may be a polyester. The fibresubstrate may be PES. The fibre substrate may comprise a mixture of apolyester with a fibre selected from cotton, wool, silk and polyurethane(e.g. Lycra®). The fibre substrate may comprise a mixture of PES with afibre selected from cotton, wool, silk and polyurethane (e.g. Lycra®).

The fibre substrate may comprise silk or wool fibres.

It may be that the fibre substrate comprises both polyester fibres andat least one other type of fibre selected from cotton, regeneratedcellulose, wool, silk, polyamide, a different polyester,polyvinylchloride, polyacrylonitrile, mohair, cashmere and apolyurethane. The fibre substrate may comprise a material that is ablend of polyester fibres and at least one fibre selected from othertype of fibre selected from cotton, regenerated cellulose, wool, silk,polyamide, a different polyester, polyvinylchloride, polyacrylonitrile,mohair, cashmere and a polyurethane. The fibre substrate may be amaterial that is a blend of polyester fibres and at least one fibreselected from cotton, regenerated cellulose, wool, silk, polyamide, adifferent polyester, polyvinylchloride, polyacrylonitrile, mohair,cashmere and a polyurethane. Alternatively, the fibre substratecomprises a first material that comprises polyester fibres and a secondmaterial that comprises at least one fibre selected from cotton,regenerated cellulose, wool, silk, polyamide, a different polyester,polyvinylchloride, polyacrylonitrile, mohair, cashmere and apolyurethane. The fibre substrate may be a whole garment, e.g. a traineror pair of trainers, a shirt or blouse, a dress, a pair of trousers, askirt, a t-shirt etc.

It may be that the fibre substrate comprises both polyester fibres andat least one other type of fibre selected from cotton, wool, silk,mohair, cashmere and a polyurethane. The fibre substrate may comprise amaterial that is a blend of polyester fibres and at least one fibreselected from other type of fibre selected from cotton, wool, silk,mohair, cashmere and a polyurethane. The fibre substrate may be amaterial that is a blend of polyester fibres and at least one fibreselected from cotton, wool, silk, mohair, cashmere and a polyurethane.Alternatively, the fibre substrate comprises a first material thatcomprises polyester fibres and a second material that comprises at leastone fibre selected from cotton, wool, silk, mohair, cashmere and apolyurethane.

As mentioned above, the inventors have found that the methods of theinvention can be used to simultaneously colour different polymers withdifferent types and classes of colourant. In particular, the methods ofthe invention can be used to simultaneously colour (e.g. dye) differentfibres with different types and classes of colourant (e.g. dye). Thisoffers the possibility that, with judicious choice of fabric, a blendedfabric could be generated in which a pattern is designed into the weaveof the fabric and the different fibres within the weave cansimultaneously and selectively be dyed different colours. Likewise, awhole garment that is formed of two or more different materials (e.g. ashoe, for example a sports shoe or pair of sports shoes) can be dyedonce formed and the various materials can be dyed different colourssimultaneously. This would allow for the bespoke dyeing, based on thepurchaser's selected colour preferences, of a whole garment either in adistribution warehouse or in a shop.

The Colourant(s)

The at least one colourant may comprise at least one pigment.

The at least one colourant may comprise at least one dye.

The at least one colourant may be a single dye. The at least onecolourant may be mixture of two or more dyes.

Suitable dyes include disperse dyes, solvent dyes, vat dyes, sulphurdyes, mordant dyes, acid dyes, direct dyes and reactive dyes. Thedisperse dyes, solvent dyes, vat dyes, sulphur dyes, mordant dyes, aciddyes, direct dyes and reactive dyes that can be used in the methods ofthe invention include all dyes classified as such in The Colour Index™published by the Society of Dyers and Colourists (SDC) and AmericanAssociation of Textile Chemists and Colourists (AATCC). In certainembodiments, the disperse dyes, solvent dyes, vat dyes, sulphur dyes,mordant dyes, acid dyes, direct dyes and reactive dyes that can be usedin the methods of the invention may include all dyes classified as suchin The Colour Index™ on the 1 May 2017.

The at least one dye may include a disperse dye. The single dye may be adisperse dye.

The at least one dye may include an acid dye (e.g. a non-metallised aciddye or a pre-metallised acid dye). The single dye may be an acid dye(e.g. a non-metallised acid dye or a pre-metallised acid dye).

The at least one dye may include a vat dye. The single dye may be a vatdye.

The at least one dye may include a reactive dye. The single dye may be areactive dye.

The at least one dye may include a direct dye. The single dye may be adirect dye.

The at least one pigment may include a pigment selected from an organicpigment, an inorganic pigment and a metallic pigment.

Where the polymer (e.g. fibre) substrate to be coloured comprisesdifferent polymers (e.g. different fibres), a mixture of two or moreclasses or types of colourant (e.g. dye) may be used. For example, wherea fibre substrate comprises both polyester fibres (e.g. PES) and anatural fibre (e.g. cotton, silk or wool), a mixture of a disperse dye(to dye the polyester fibres) and a reactive dye (to dye the naturalfibres) might be used. Alternatively a mixture of a disperse dye (to dyethe polyester) and a direct dye (to dye the natural fibre) might beused. In a further alternative, a mixture of a disperse dye (to dye thepolyester fibres) and an acid dye (to dye the natural fibres) might beused. In a further example, where a fibre substrate comprises polyesterfibres (e.g. PES), cotton fibres and either wool or silk fibres, amixture of a disperse dye (to dye the polyester fibres), a reactive dye(to dye the cotton fibre) and an acid dye (to dye the wool or silkfibres) might be used.

The invention may further be described in the following numberedparagraphs:

-   -   1. A method of dyeing a fibre substrate, the method comprising:        -   a) subjecting the fibre substrate to a dye liquor at a            temperature T1, T1 being below 100° C., said dye liquor            comprising at least one dye dissolved in a first solvent            system to provide the fibre substrate wetted with the dye            liquor;        -   b) adding a second solvent system to the fibre substrate            wetted with the dye liquor, without raising the temperature            above a temperature T2, T2 being below 100° C., to provide            the dyed fibre substrate wetted with a mixture of the first            solvent system and the second solvent system; and        -   c) separating the dyed fibre substrate from the mixture of            the first and second solvent systems and any remaining dye;            wherein the dye or each dye is more soluble in the first            solvent system than in the second solvent system.    -   2. A method of paragraph 1, wherein the step of adding the        second solvent system comprises adding the second solvent system        portionwise to the mixture of the fibre substrate and the dye        liquor.    -   3. A method of paragraph 1 or paragraph 2, wherein the second        solvent system comprises water.    -   4. A method of paragraph 3, wherein the second solvent system is        water.    -   5. A method of any preceding paragraph, wherein the first        solvent system and the second solvent system are miscible.    -   6. A method of any preceding paragraph, wherein the first        solvent system is an organic solvent or a mixture of one or more        organic solvents.    -   7. A method of paragraph 6, wherein the first solvent system is        a polar organic solvent or a mixture of polar organic solvents.    -   8. A method of paragraph 7, wherein the first solvent system is        acetone.    -   9. A method of any preceding paragraph, wherein the fibre        substrate comprises fibres selected from: a polyester, nylon, a        polyurethane, wool, silk, cotton or a mixture thereof.    -   10. A method of paragraph 10, wherein the fibre substrate        comprises polyester fibres or a mixture of a polyester with a        fibre selected from cotton, wool, silk and a polyurethane 11. A        method of any preceding paragraph, wherein the ratio of the        total volume of the first solvent system to the total volume of        the second solvent system may be in the range 1:2 to 1:20.    -   12. A method of paragraph 11, wherein the ratio of the total        volume of the first solvent system to the total volume of the        second solvent system may be in the range 30:70 to 10:90.    -   13. A method of any preceding paragraph, wherein the weight        ratio of the fibre substrate to the first solvent system is in        the range from 3:1 to 1:3.    -   14. A method of any preceding paragraph, wherein the at least        one dye is a disperse dye.    -   15. A method of any preceding paragraph, wherein the method        comprises dissolving the at least one dye in the first solvent        system to form the dye liquor 16. A method of any preceding        paragraph, wherein the dye liquor does not comprise a dispersing        agent.    -   17. A fibre substrate obtainable according to the method of any        preceding paragraph.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are further described hereinafter withreference to the accompanying drawings, in which:

FIG. 1 shows the high temperature (HT) PES dyeing method used as acomparator in the Examples below;

FIG. 2 shows the reduction clearing process employed for the Examples;

FIG. 3 provides a general depiction of controlled precipitation dyeingmethod of the invention;

FIG. 4 shows the colour strength of 2% omf dyeings on PES achieved usingcontrolled precipitation method of the invention; Teratop Yellow HL-G150%; 120 mins at 98° C.;

FIG. 5 shows the colour strength of 2% omf dyeings on PES achieved usingcontrolled precipitation method of the invention; Teratop Yellow HL-G150%; 30′, 60′ and 90′ at 98° C.;

FIG. 6 shows the colour strength of 2% omf dyeings on PES achieved usingcontrolled precipitation method of the invention for 20 mins at 98° C.;Teratop Yellow HL-G 150%;

FIG. 7 shows the colour strength of 2% omf dyeings on PES achieved usingcontrolled precipitation method of the invention for 120 mins at 85° C.;Teratop Yellow HL-G 150%;

FIG. 8 shows the colour strength of 2% omf dyeings on PES achieved usingcontrolled precipitation method of the invention for 20 mins at 98° C.(Teratop Blue HL-G 150%: left and Teratop Pink HL-G 150%: right);

FIG. 9 shows the dyeing method used for the dyeing methods described inExamples 3, 4 and 5;

FIG. 10 shows the colour strength of 2% omf dyeing of crude gradeTeratop Yellow HL-G 150% on a fabric composite comprising polyesterfabric attached to scoured PA 66 fabric;

FIG. 11 shows the colour strength of 2% omf dyeings of commercialTeratop Yellow HL-G 150% on PES as a function of dyeing temperatureusing DMSO as solvent

DETAILED DESCRIPTION

Organic solvents are organic compounds that are liquids at roomtemperature and atmospheric pressure. Typically, organic solvents arecompounds that comprise both carbon atoms and hydrogen atoms. Oneexception to this is carbon tetrachloride. Organic solvents may alsocomprise oxygen, nitrogen, chlorine, fluorine or sulphur.

The term ‘wetted’ is used in this specification to mean that the polymer(e.g. fibre) substrate is in contact with a liquid, e.g. the dye liquoror the mixture of the first solvent system and the second solventsystem. It may mean that the substrate (e.g. fibre substrate) is soakedin the liquid, e.g. saturated with the liquid. It may mean that thesubstrate (e.g. fibre substrate) is coated in the liquid. It may meanthat the substrate (e.g. fibre substrate) is immersed in the liquid.Other techniques that could be used include spraying, soaking,vapourisation, imbibition, etc.

The polymer (e.g. fibre) substrate is described as ‘coloured’ where thecolourant molecules have become absorbed into the substrate (e.g. intothe fibres). Throughout the description and claims of thisspecification, the words “comprise” and “contain” and variations of themmean “including but not limited to”, and they are not intended to (anddo not) exclude other moieties, additives, components, integers orsteps. Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The invention is notrestricted to the details of any foregoing embodiments. The inventionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

EXAMPLES General Methods Materials

Scoured poly(ethylene terephthalate) (PES) fabric (120 gm⁻²), scoured,bleached and mercerised woven cotton fabric (180 gm⁻²) and scoured PA 66fabric (116 gm⁻²) was obtained from Whaleys (Bradford, UK). Commercialgrade as well as crude grade (ie as-synthesised) samples of threedisperse dyes, namely Teratop Yellow HL-G 150%, Teratop Blue HL-G 150%and Teratop Pink HL-G 150% were kindly provided by Huntsman(Switzerland). Commercial dyes were used in this work so as to reflectcommercial dyeing practice whilst equivalent crude grade dyes were alsoused to determine whether it would be possible to dye PES usingdispersant-free disperse dyes. The three dyes used were chosenarbitrarily as being representative of modern commercial disperse dyes.A 2% omf depth of shade was used for each of the three dyes as thisprovided typical pale/medium depth dyeings.

Samples of Polysorbate 20, Polysobate 60, Polysorbate 80, Lecithin andSuperclean were obtained from Sigma-Aldrich. All other chemicals were ofgeneral purpose grade.

From measured values of the relative dye contents of the respectivepairs of commercial grade and crude grade dye samples, the amount ofcrude grade dye employed in dyeing was adjusted so that the depth ofshade obtained (ie 2% omf) was the same as that secured using thecommercial grade dye, was obtained.

Comparative General Method

The high temperature (HT) dyeing method used for comparison in this workis shown in FIG. 1.

The PES fabric (5 g or 10 g) was dyed using both the commercial gradeand grade crude disperse dyes following the procedure shown in FIG. 1.At the end of dyeing, the dyed sample was removed from the dyebath,squeezed to remove surplus dye liquor and rinsed in water according tothe procedure depicted in FIG. 1. The dyed sample was then squeezed oncemore and subjected to the reduction clear procedure displayed in FIG. 2.At the end of the reduction clearing process the sample was removed,squeezed to remove surplus liquor and rinsed in cold water as shown inFIG. 2. The reduction cleared dyeing was squeezed and allowed to dry inthe open air.

General Method of the Invention

The controlled precipitation method of the invention is illustrated in ageneral sense in FIG. 3.

Example 1—Development of the Methodology Using Disperse Dyes, PES andAcetone

The method depicted in FIG. 3 was carried out with a₁; a₂; a₃; a₄=10 cm³water; t₁=30′; t₂=30′; a₃=30′; a₄=30′; x=98° C.

The disperse dye was dissolved in a given volume (in this case 10 cm³)of acetone and the ensuing solution was applied to the PES fibre.

When the temperature of the dyebath reached 98° C., a volume (10 cm³) ofwater was added and dyeing continued for a certain period of time, afterwhich a further 10 cm³ of water was added. This process continued untilthe final dyebath volume was 50 cm³, corresponding to a 1:10 liquorratio. Thus, over the length of the dyeing process, the ratio ofwater:acetone was gradually increased from 0:100 at the start of dyeingto 80:20 at the end of dyeing.

Without wishing to be bound by theory, the purpose of progressivelyintroducing water to the acetone dye solution was to gradually force thedisperse dye to precipitate out of solution in a controlled manner, soas to achieve increased dye-fibre substantivity and, thus, increased dyeuptake, in a controlled and measured manner.

Following the procedure just described, the total dyeing time at 98° C.was 120 mins. FIG. 4 reveals that using this approach, the ensuingdyeing displayed very high colour strength, which was considerablygreater than that secured using the commercial grade dye and theconventional HT dyeing method at 130° C. Visual inspection revealed thatthe dye precipitation method of the invention not only provided a deeperdepth of shade than the HT method but, significantly, the level ofdyebath exhaustion secured was much greater.

Thus the higher colour strength of the 120 mins 98° C. dyeing (FIG. 4)can be attributed to the greater extent of dye exhaustion achieved. Thefact that the residual dyebath was essentially free of unexhausteddisperse dye offers obvious cost and environmental potential. In otherwords, in order to achieve a colour strength that is equivalent to thatfurnished using a commercial grade dye employing a conventional 2% omfdyeing method at 130° C. (ie an f_(k) value of ˜50) will require lessdisperse dye, if the controlled precipitation dyeing method of theinvention is used (ie ˜1.25% omf dye), because virtually 100% dyeexhaustion is achieved. Furthermore, because crude grade disperse dyewas used for the precipitation dyeing method of the invention, then theexhausted dyebath will contain essentially no dye, zero dispersing agentand zero levelling agent, compared to the residual dyebath that willensue from the conventional HT dyeing method.

Attempts were made to reduce the length of dyeing time at 98° C.; forthis, in FIG. 3, a₁, a₂, a₃ and a₄=10 cm³ water and the total time atthe commercial boil was 90 min, 60 min and 30 min (in all casesa₁=a₂=a₃=a₄. As FIG. 5 shows, reducing the dyeing time at 98° C. did notaffect the colour yield of the ensuing dyeings; a comparison of FIGS. 4and 5 shows that the colour yields of all four dyeings were the same.

When the total time at the commercial boil was further reduced to 20mins (ie, a₁, a₂, a₃ and a₄=10 cm³ water and a₁=a₂=a₃=a₄=5′) the colourstrength of the dyed fabric was similar to that achieved for dyeingtimes of 30, 60, 90 and 120 mins (FIG. 6). However, with furtherreduction of dyeing time at the commercial boil the colour strength ofthe dyeings reduced.

When the temperature of dyeing was lowered from 98° C. to 85° C., it wasfound (FIG. 7) that whilst the colour strength of dyeings carried outfor 120 min were the same as those achieved at 98° C., shorter dyeingtimes at 85° C. of 60 min and 90 min produced dyeings that were of lowercolour strength. As observed for dyeings undertaken at the commercialboil, the residual dyebath obtained after 120 min at 85° C. was observedon visual inspection to be devoid of dye.

When two other disperse dyes, namely Teratop Blue HL-G 150% and TeratopPink HL-G 150%, were applied to PES using the precipitation dyeingmethod of the invention for 20 min at 98° C., and the colour strengthsof the dyeings were compared to those secured using the HT dyeing method(ie at 130° C.) are shown in FIG. 8.

It is apparent that for each of the dyes, higher colour strength dyeingswere achieved using the precipitation dyeing method of the invention at98° C. (FIG. 8) and, also, that the extent of dye exhaustion observed,was much higher for the HT dyeing method.

Example 2—Fastness

Table 1 shows that 2% omf dyeings obtained using the three commercialgrade dyes when applied using the HT method (i.e. 130° C.) displayedvery good fastness to washing at 60° C., as expected; visual inspectionalso showed the impressive depths of shade of the dyeings after washfastness testing. The results presented in Table 1 also reveal that thecorresponding dyeings which had been produced using crude grade samplesof the three dyes employing the precipitation dyeing method of theinvention at 98° C. for 20 min displayed essentially the same high levelof wash fastness. The latter findings are impressive when it is recalledthat the colour strength of the 98° C. dyeings were much greater thanthat of their 130° C. counterparts. Thus, as expected, the manner bywhich the disperse dyes were applied (ie differences in dyeingtemperature, dyeing duration and acetone) had no effect on washfastness.

TABLE 1 fastness of 2% omf dyeings on PES produced using the HT method(commercial grade dyes at 130° C.) and 20 min precipitation method ofthe invention at 98° C., to ISO 105-C06/C2S (60° C.) Teratop HL- dyeingchange bleached G 150% grade temp/° C. in shade wool acrylic polyesterpolyamide cotton Diacetate Yellow commercial 130 5 5 5 5 4/5 5 4.5 crude98 5 5 5 5 4.5 5 4.5 Blue commercial 130 4/5 4/5 5 4 5   5 4/5 crude 984/5 4/5 5 4 4/5 5 4/5 Pink commercial 130 5 4 5 4 4/5 5 4/5 crude 98 5 45 4 4/5 5 4/5

When the above method was followed but using polyester fabric which hadbeen previously wetted-out using water and squeezed to remove surpluswater, the colour strength of the ensuing dyeing obtained for 20 min at98° C. was comparable to that achieved using dry polyester fabric.

Example 3—Other Fabrics and Other Classes of Dyes

The methods of the invention can also be used to dye other substratesusing other dye types. The following example describes the dyeing ofwool, silk and polyamide substrates with acid dyes and a disperse dye.

The general method used throughout this example is shown in FIG. 9. ARoaches Pyrotec S dyeing machine) was used. 0.1 g of commercial dye wasdissolved in 10 cm³ acetone and the ensuing solution was placed in a 300cm³ capacity dye tube, followed by 5 g of fabric. The sealed dye tubewas heated to 85° C. and then 10 cm³ of water was injected into thedyeing tube. A further total of 40 cm³ of water was injected at timeintervals, as shown in FIG. 9. The total dyeing time at 85° C. was 20min.

Both non-metallised acid (Erionyl Red A-28F (Huntsman)) and 1:2pre-metallised acid dyes (Supralan Yellow 4GL (Dystar); Lanaset Yellow2R (Huntsman) and Neutrilan Yellow A-3R (Yorkshire)) were applied towool, silk and PA fabrics using the dyeing methods of the invention. Inaddition, both commercial grade as well as crude grade samples of thedisperse dye Teratop Yellow HL-G 150% (Huntsman) was applied to wool, PAand wool fibres.

Both silk and wool were successfully dyed at 85° C. in 20 min using thenon-metallised dye Erionyl Red A-28F. colour measurement L*=34.3 a*=63.4b*=58.1

In comparison to the conventional method for dyeing wool with such dyetypes, which is normally carried out at higher temperature (for wool:98° C.) under acidic conditions for 60-90 min, the novel dyeing methodis advantageous insofar as it enables the fibres to be dyed at a lowertemperature of 85° C. (for wool) in a short time (ie 20 min) withoutrecourse to pH adjustment, thereby offering savings in time, energy andchemicals.

Both silk and wool were successfully dyed at 85° C. for 20 min using the1:2 metal complex dye Supralan Yellow 4GL at 85° C. for 20 min using thenovel dyeing method colour measurement L*=83.8 a*=6.9 b*=116.5. Onceagain, compared to the conventional method for dyeing wool with such dyetypes, which is normally carried out at higher temperature (for wool:98° C.) under acidic conditions for 60-90 min, the novel dyeing enablesthe fibres to be dyed at 85° C. in a short time (ie 20 min) and withoutusing pH adjustment, thereby offering savings in time, energy andchemicals.

The novel dyeing method also enabled wool and silk to be dyed at 85° C.for 20 min using the 1:2 metal complex dyes Neutrilan Yellow A-3R colourmeasurement L*=48.7 a*=34.5 b*=8.1 and Lanaset Yellow 2R. Once again,compared to the conventional method for dyeing wool with such dye types,which is normally carried out at higher temperature (for wool) underacidic conditions for 60-90 min, the novel dyeing enables the fibres tobe dyed at 85° C. in a short time (ie 20 min), thereby offering savingsin time, energy and chemicals.

Both commercial (i.e. containing dispersants) and crude (i.e. notcontaining dispersants) samples of the disperse dye Teratop Yellow HL-G150% were successfully applied to both scoured wool and silk and PAfibres using the novel dyeing method at 85° C. and 20 min.

Example 4—Blends of Fibres

The methods of the invention can also be used to dye a combination ofdifferent types of fibre. The following example describes the dyeing ofpolyester/cotton blends as well as polyester/Nylon blends using dispersedye.

The general method used throughout this example is shown in FIG. 9. ARoaches Pyrotec S dyeing machine) was used. The appropriate amount ofcrude grade disperse dye to provide a 2% omf shade was dissolved in 10cm³ acetone and the ensuing solution was placed in a 300 cm³ capacitydye tube, followed by a fabric composite comprising 2.5 g of polyesterfabric attached to 2.5 g of scoured, bleached and mercerised wovencotton fabric. The sealed dye tube was heated to 98° C. and then 10 cm³of water was injected into the dyeing tube. A further total of 40 cm³ ofwater was injected at time intervals, as shown in FIG. 9. The totaldyeing time at 85° C. was 20 min.

2% omf dyeings of the crude (i.e. not containing dispersants) dispersedyes Teratop Yellow HL-G 150%, Teratop Blue HL-G 150% and Teratop PinkHL-G 150%, were successfully achieved using the novel dyeing method at98° C. and 20 min. Whilst the polyester component was fully dyed, thecotton fabric was uncoloured. This was anticipated based on the relativehydrophobicity of the cotton and polyester fibres and the correspondingdifferent substantivity for the fibres displayed by the disperse dye.

Following the method described above, a 2% omf dyeing using the crudegrade disperse dye Teratop Yellow HL-G 150% was obtained using a fabriccomposite comprising 2.5 g of polyester fabric attached to 2.5 g ofscoured PA 66 fabric.

Both the polyester and nylon 66 fabrics were dyed, as shown by FIG. 10,but the polyester was of higher depth of shade, as expected, owing tothe greater hydrophobicity of the polyester material and thecorresponding greater substantivity displayed by the dye towards thepolyester fibre.

Example 5—Solvent Mixtures

The first solvent can comprise a mixture of two or more organic solventsor a mixture of water and an organic solvent.

The general method used throughout this example is shown in FIG. 9, withthe acetone replaced with mixed solvent systems as described below. ARoaches Pyrotec S dyeing machine) was used. Crude grade disperse dyeTeratop Yellow HL-G 150%, was dissolved in a mixture of 10 cm³ acetoneand 2 cm³ of water. The ensuing solution was placed in a 300 cm³capacity dye tube, followed by polyester fabric. The sealed dye tube washeated to 98° C. and then 10 cm³ of water was injected into the dyeingtube. A further total of 40 cm³ of water was injected at time intervals.The total dyeing time at 98° C. was 20 min.

The colour strength of the ensuing dyeing was very similar to thatobtained when acetone only had been used as the first solvent.

When the above method was used but crude grade disperse dye TeratopYellow HL-G 150% was dissolved in a mixture of 4 cm³ acetone and 6 cm³of ethanol, successful dyeing was achieved.

Example 6—Other Solvents

Although acetone is an excellent solvent for crude grade disperse dyes,other, higher boiling solvents were examined. Being higher boiling,these solvents offer a reduced fire risk compared to acetone.

Different amounts (5, 10 and 20 cm³) of DMSO were used to dissolve 2%omf commercial Teratop Yellow HL-G and different amounts of water (45,40 and 30 cm³) were added portionwise so as to achieve a 1:10 LR overallwere used. The colour strength of the dyed polyester is shown in FIG. 11

From FIG. 11 it is apparent that lower values of colour strength areobtained in comparison to that of PES which had been dyed using acetone,which can be attributed to the lower solubility of the dye in DMSO.However, as FIG. 11 shows, by increasing the amount of DMSO employed,higher colour strength dyeings were achieved. While these dyeings didnot exhibit the high colour strengths of the acetone processes, theystill offer benefits in terms of lower temperature of process with lowerenergy use and the ability to dye PES concurrently with non-PES fibres.

Various other high boiling point solvents were used to dye PES at a 2%omf depth of shade of crude Teratop Yellow HL-G, namely ethylene glycoldiacetate (EGD), triethylene glycol monomethyl ether (TGM), dipropyleneglycol methyl ether (DME) and 1-methoxy-2-propanol.

Samples of PES fabric were dyed at 95° C. using the controlledprecipitation dyeing method shown in FIG. 3, employing each of the abovesolvents (10 cm³) and 4 additions of water (40 cm³ water in total; 1:10LR in total), the total dyeing time at 95° C. being 20 mins.

Colour measurement data (illuminant D₆₅; specular included; UV excluded;10° standard observer)

triethylene glycol monomethyl ether (TGM) L*=88.9a*=30.5b*=95.3

ethylene glycol diacetate (EGD) L*=86.1a*=19.1b*=80.1

Each of the four solvents were able to dissolve the crude disperse dyeand can be utilised in the precipitation dyeing method.

Example 7—Vat Dyes

To investigate whether the novel precipitation dyeing method could beused to apply to vat dyes, indigo was selected. Samples of PES fabricwere dyed at 95° C. using the controlled precipitation dyeing methodshown in FIG. 3, employing acetone as solvent (10 cm³) and 4 additionsof water (40 cm³ water in total; 1:10 LR in total), the total dyeingtime at 95° C. being 20 mins.

It was found that the vat dye could be applied from acetone using theprecipitation dyeing method.

No reductants or pH adjustments were needed to achieve this result.

Colour measurement data (illuminant D₆₅; specular included; UV excluded;10° standard observer)

L*=55.9 a*=−6.3 b*=−10.9

Example 8—One Pot Dyeing of Mixtures of Fibres with Mixtures of Classesof Dyes

The novel precipitation dyeing method may offer the potential for dyeingfibre blends using different classes/types of dye simultaneously, in thesame dyebath, in the absence/much reduced amounts of dyebathauxiliaries.

For this example, samples (2.5 g) of fabric were dyed at differenttemperatures using the controlled precipitation dyeing method shown inFIG. 3, employing acetone as primary solvent and using additions ofwater or solutions of inorganic electrolyte or alkali, as well aselectrolyte/alkali, the total dyeing time being 20 mins. The amounts aregiven in the examples below

PES/Cotton Using Reactive Dye and Disperse Dye

Duractive Black B (C.I. Reactive Black 5) and crude Teratop Yellow HL-Gwere dissolved in acetone. Separate samples of PES fabric and cottonfabric were dyed together at 95° C. using the controlled precipitationdyeing method shown in FIG. 3, employing 4 additions of either a) wateror b) a solution comprising 15 gl⁻¹ Na₂CO₃ and 50 gl⁻¹ NaCl (1:10 LR intotal), the total dyeing time being 20 mins.

It was found that it is possible to dye both the hydrophobic PES andhydrophilic cotton substrates in the same dyebath in 20 minutes at 95°C., using a mixture of non-ionic disperse dye and anionic reactive dye.As expected the colour yield secured using both electrolyte and alkalifavoured reactive dye uptake.

Since it is now known that reactive dye exhaustion on cotton in theabsence of added inorganic electrolyte can be increased through the useof low liquor ratio, dyeings were also made using two 10 cm³ additions(1:6 LR) of a solution comprising 15 gl⁻¹ Na₂CO₃; an improvement indepth of shade of the reactive dye on the cotton component was achievedcompared to that obtained at a 1:10 LR.

To samples of PES fabric and cotton fabric Commercial Novacron RedFN-2BL was applied in conjunction with crude Teratop Yellow HL-Gdissolved in acetone. Four 10 cm³ additions of a solution comprising 15gl⁻¹ Na₂CO were made (1:10 LR); the total dyeing time was 20 mins at 95°C. It was found that the precipitation method enables PES and cottonsubstrates to be dyed in the same dyebath in 20 minutes at 95° C., usinga mixture of disperse dye and reactive dye.

Colour Measurement

PES L*=75.8 a*=18.9 b*=116.5

cotton L*=52.9 a*=4.3 b*=−19.8

PES/Cotton Using Direct Dye and Disperse Dye

C.I. Direct Red 81 and crude Teratop Yellow HL-G were dissolved inacetone. Samples of PES fabric and cotton fabric were dyed at 95° C.using the controlled precipitation dyeing method shown in FIG. 3,employing 4 additions of water or a solution containing 20 gl⁻¹ NaCl(1:10 LR in total), the total dyeing time being 20 mins.

Colour Measurement

PES L*=73.1 a*=16.1 b*=117.6

cotton L*=41.1 a*=66.9 b*=19.4

Dyeings were also made using two 10 cm³ additions (1:6 LR) of water

Colour Measurement

PES L*=78.4 a*=35.8 b*=111.9

cotton L*=52.3 a*=61.6 b*=11.2

It was found that both PES and cotton fibres can be dyed simultaneouslyin the same dyebath in 20 minutes at 95° C., using a mixture of dispersedye and direct dye; as expected the colour yield secured usingelectrolyte favoured dye uptake, and using a lower liquor ratio (ie 1:6)improved direct dye adsorption in the absence of added inorganicelectrolyte.

PES/Wool Using Non-Metallised and Pre-Metallised Acid Dyes inConjunction with Disperse Dye

Commercial samples of either a) the non-metallised acid dye Erionyl RedA-28F or b) the 1:2 pre-metallised acid dye Neutrilan Yellow A-3R weredissolved in acetone along with crude (i.e. containing no auxiliaries)Teratop Yellow HL-G. Samples of PES fabric and wool fabric were dyed at85° C. using the controlled precipitation dyeing method shown in FIG. 3,employing 4 additions of water (1:10 LR in total), the total dyeing timebeing 20 mins.

It was found that PES and wool fibres can be dyed simultaneously in thesame dyebath in 20 minutes at 85° C., using a mixture of disperse dyeand either non-metallised acid or pre-metallised acid dyes in theabsence of all dyeing auxiliaries. The wool fabric component was dyedeither a red colour or yellow colour depending on the type of acid dyesused, and the polyester fabric component was dyed a yellow colour

PES/Silk Using Non-Metallised and Pre-Metallised Acid Dyes inConjunction with Disperse Dye

Commercial samples of either a) the non-metallised acid dye Erionyl RedA-28F or b) the 1:2 pre-metallised acid dye Neutrilan Yellow A-3R weredissolved in acetone along with crude (i.e. containing no auxiliaries)Teratop Yellow HL-G. Samples of PES fabric and silk fabric were dyed at85° C. using the controlled precipitation dyeing method shown in FIG. 3,employing 4 additions of water (1:10 LR in total), the total dyeing timebeing 20 mins.

It was found that PES and wool fibres can be dyed simultaneously in thesame dyebath in 20 minutes at 85° C., using a mixture of disperse dyeand either non-metallised acid or pre-metallised acid dyes in theabsence of all dyeing auxiliaries. The silk fabric component was dyedeither a red colour or yellow colour depending on the type of acid dyesused, and the polyester fabric component was dyed a yellow colour

PES/Cotton/Wool Using Non-Metallised Acid and Reactive Dyes inConjunction with Disperse Dye

Commercial samples of the non-metallised acid dye Erionyl Red A-2BF andDuractive Black B were dissolved in acetone along with with crudeTeratop Yellow HL-G. Samples of PES fabric, wool fabric and cottonfabric were dyed at 85° C. using the controlled precipitation dyeingmethod shown in FIG. 3, employing 4 additions of water (1:10 LR intotal), the total dyeing time being 20 mins.

The cotton fabric component was dyed a blue colour, the wool fabric wasdyed a red colour and the polyester fabric component was dyed a yellowcolour.

The results showed that PES, wool and cotton fibres can be dyeddifferent colours simultaneously in the same dyebath in 20 minutes at85° C., using a mixture of disperse dye, reactive dye and non-metallisedacid dye in the absence of all dyeing auxiliaries.

Example 8—One Pot Dyeing of a Solid Object

This example describes the results obtained from dyeing 3D printed nylon12 (PA12) with a disperse dye (Dianix Blue-ACE) at the boil (98° C.)under atmospheric pressure, using two different solvent systems. Thedyed samples obtained were compared in terms of depth of shade and theprocess conditions employed (i.e. temperature, solvent system employed).

The substrate dyed were white solid, 3D printed nylon 12 parts.

The dye used in this trial was of commercial grade and was used assupplied without purification; Dianix Blue ACE manufactured by Dystar.

Photographs of all samples were recorded in a light cabinet under D₆₅illuminant, using a Samsung Galaxy S6+ mobile phone camera.

All dyeing was carried-out by placing the dye, substrate and solvent ina container placed on a hot plate and heated to the required processingtemperature. The temperature of the dyebath was measured using amercury-in-glass thermometer.

Solvent System 1 (Water)

A 2% omf (Dianix Blue-ACE) dyeing was produced following the procedureshown in FIG. 12A, employing a 10:1 LR. At the end of dyeing, the samplewas rinsed thoroughly under running tap water and dried in the open air.A photograph of the dyed sample is shown in FIG. 12B

Solvent System 2 (Water:Glycerol; 80:20)

A 2% omf (Dianix Blue-ACE) was produced following the procedure shown inFIG. 12C, employing a 10:1 LR (liquor comprising of water:glycerol;80:20) At the end of dyeing, the samples was rinsed thoroughly underrunning tap water and dried in the open air. A photograph of the dyedsample is shown in FIG. 12D

Upon visual inspection of the dyed samples it was apparent that, thesample obtained using the glycerol: water solvent system had the highestdepth of shade (compare FIG. 12B and FIG. 12D).

1. A method of colouring a polymer substrate, the method comprising: a)subjecting the polymer substrate to a colouring liquor at a temperatureT1, T1 being below 100° C., said colouring liquor comprising at leastone colourant dissolved in a first solvent system to provide the polymersubstrate wetted with the colouring liquor; b) adding a second solventsystem to the polymer substrate wetted with the colouring liquor,without raising the temperature above a temperature T2, T2 being below100° C., to provide the coloured polymer substrate wetted with a mixtureof the first solvent system and the second solvent system; and c)separating the coloured polymer substrate from the mixture of the firstand second solvent systems and any remaining colourant; wherein thecolourant or colourant dye is more soluble in the first solvent systemthan in the second solvent system.
 2. (canceled)
 3. (canceled)
 4. Amethod of claim 1, wherein the second solvent system is water.
 5. Amethod of claim 1, wherein the first solvent system and the secondsolvent system are miscible.
 6. (canceled)
 7. A method of claim 1,wherein the first solvent system is a polar organic solvent or a mixtureof polar organic solvents.
 8. A method of claim 7, wherein the firstsolvent system comprises acetone.
 9. A method of claim 7, wherein thefirst solvent system comprises a solvent selected from glycerol,ethylene glycol diacetate (EGD), triethylene glycol monomethyl (TGM),dipropylene glycol methyl ether (DME) and 1-methoxy-2-propanol.
 10. Amethod of claim 1, wherein the polymer substrate is a fibre substrate.11. A method of claim 10, wherein the fibre substrate comprises fibresselected from: a polyester, nylon, a polyurethane, wool, silk, cotton ora mixture thereof.
 12. A method of claim 11, wherein the fibre substratecomprises polyester fibres.
 13. A method of claim 12, wherein the fibresubstrate comprises polyester fibres and at least one fibre selectedfrom cotton, regenerated cellulose, wool, silk, polyamide, a differentpolyester, polyvinylchloride, polyacrylonitrile, mohair, cashmere and apolyurethane.
 14. A method of claim 13, wherein the fibre substratecomprises a material that is a blend of polyester fibres and at leastone fibre selected from cotton, regenerated cellulose, wool, silk,polyamide, a different polyester, polyvinylchloride, polyacrylonitrile,mohair, cashmere and a polyurethane.
 15. A method of claim 14, whereinthe fibre substrate comprises a first material that comprises polyesterfibres and a second material that comprises at least one fibre selectedfrom cotton, regenerated cellulose, wool, silk, polyamide, a differentpolyester, polyvinylchloride, polyacrylonitrile, mohair, cashmere and apolyurethane.
 16. A method of claim 15, wherein the fibre substrate is awhole garment.
 17. A method of claim 1, wherein the ratio of the totalvolume of the first solvent system to the total volume of the secondsolvent system is in the range 1:2 to 1:20.
 18. A method of claim 16,wherein the ratio of the total volume of the first solvent system to thetotal volume of the second solvent system is in the range 30:70 to10:90.
 19. A method of claim 1, wherein the weight ratio of the polymersubstrate to the first solvent system is in the range from 3:1 to 1:3.20. A method of claim 1, wherein the at least one colourant is at leastone dye.
 21. A method of claim 20, wherein the at least one dye is adisperse dye.
 22. A method of claim 1, wherein the method comprisesdissolving the at least one colourant in the first solvent system toform the colouring liquor
 23. A method of claim 1, wherein the colouringliquor does not comprise a dispersing agent.
 24. (canceled)